Not sure if this is the right place to post this but here goes
I installed a 4 way TV signal splitter under the house a few months ago.
The signal is split 4 ways 3 go to the individual bedrooms and on the the lounge.
The splitter is a passive (no power) all metal casing (Obviously for shield)
To cut a long story short I was under the house today and touched the device and got a boot .
I went and got my trusty multi meter and measured between the device and a copper gas pipe (assuming the gas pipe was a good earth)
To my surprise It measured around 112Vac.
As I said the device is passive and no power injection anywhere I cannot see how this is possible apart from a faulty TV??
Look Here -> |
This 112 Volts or so is quite commonly measurable on the metal casing of modern equipment having 2 wire mains leads.
Often it is capacitively coupled from the mains by the (high-frequency) bypass capacitors to the chassis and has a relatively high source impedance. In other words you can't pull very much current from the device and it's unlikely to hurt you.
HOWEVER, this same relatively low-power source can wreak havoc with other delicate electronics - you should ALWAYS unplug the mains when moving, removing or adding connections such as A/V inputs/outputs - or in the case of satellite gear - the connections to LNBs and DiSEqC (etc.) switches. In the satellite equipment case the centre pin of F type plugs makes contact before the earth parts of the connection takes place, putting this possible 112 VAC into electronics designed for a maximum of 18 Volts DC....nasty ! RCA leads for A/V connections also connect the centre active pin before the earthy side, that's why you can hear a loud buzz when plugging in audio equipment when it's turned on....LG CTVs hate this !
High-frequency AC from Switch Mode Power Supplies can be capacitively coupled across the SMPS transformer windings, often this can be felt as a burning sensation rather than a "tingle", and again is unlikely to hurt you personally, but you can get hurt by the jump reflex - I stuck a pair of sidecutters into the ceiling tiles once under similar conditions..
UNPLUG before moving connections !
I'd be grounding the earth of you antenna system
Bookmarks